People take dietary supplements for various reasons. Some want to increase their energy or help with weight loss. Others simply want to enhance their overall health.

Dietary supplements are just what the name suggests. They contain ingredients to supplement—or add to—your diet. The ingredient could be a vitamin, mineral, amino acid, herb, or enzyme. Dietary supplements usually come in pill, liquid or powder form. You can buy some as a tea or extract to drink. Others come as a nutrition bar or a chew.

It’s important to realize any dietary supplement has the potential to cause problems. And some can have harmful side effects. That’s especially true if you combine them with certain prescription medications or if you have an existing medical problem. Learn the answers to the following questions before taking any dietary supplement.

What are the benefits?

Dietary supplements can be beneficial. Some may help reduce the risk for certain diseases. Others may help you be healthier overall.

For instance, your body needs vitamin D. It’s important for healthy bones. But, it can be hard to get enough of this vitamin naturally. Taking a supplement provides an extra source of vitamin D. Another example is folic acid. Taking it before and during early pregnancy helps prevent certain birth defects.

Check with your doctor before starting a supplement to find out about the specific benefits for you.

Eye experts suggest boosting outdoor time to get young eyes focusing on distant objects

Children who spend lots of time indoors and on computers and other electronic devices may be raising their risk for nearsightedness, a panel of U.S. ophthalmology experts suggests.

The prevalence of Americans with nearsightedness — also known as myopia — has nearly doubled over the last 50 years, the ophthalmologists noted.

The ophthalmologists suspect the increase is due to “near work” — focusing on something close to your eyes — and the decreased amount of time spent outdoors in natural light.

“Kids are spending much more time doing indoor activities with their cellphones, iPads, computers, and so on,” said Dr. Rohit Varma, director of the University of Southern California Eye Institute in Los Angeles.

“Especially when children are young, when they play these games indoors where they’re seeing things very close to them and doing it in low-light level — that combination of doing near activities in low light is what contributes to these children becoming very nearsighted,” Varma said.

A panel of 10 ophthalmology experts discussed the global increase of childhood myopia at the American Academy of Ophthalmology’s (AAO) recent annual meeting in Las Vegas. Information presented at meetings is usually viewed as preliminary until published in a peer-reviewed journal.

Anyone can be nearsighted, but it’s more common in people whose parents are nearsighted, said Dr. K. David Epley, a spokesman for the AAO. The condition is also much more prevalent in industrialized and urban areas than in rural areas, he added.

Children of East Asian descent are genetically predisposed to nearsightedness, but children’s habits in those regions may be increasing the rates of myopia even more. The current rate of myopia in young people in China is 90 percent compared to about 10 to 20 percent 60 years ago, the experts said. That compares to a rate of 42 percent for Americans between the ages of 12 and 54, according to previous research.

The ophthalmologists noted the difference in Chinese and American work habits. Children in China spend up to 12 hours a day doing near work, compared to their U.S. peers, who spend about nine hours a day on near work, the eye experts said.